Joysticks are well known devices for controlling movement of devices or symbols. Joysticks are commonly used in video games, for example, to effect real or simulated movement of game characters or symbols on a video display. Generally, joysticks consist of a lever mounted for pivotal movement between various radial positions, wherein electrical output signals corresponding to the joystick positions are communicated to a controller (e.g., game controller). The controller, in turn, processes the electrical signals and, according to a game program, manipulates the character(s) or symbol(s) under control corresponding to the various positions of the joystick.
Generally, the types and degree of control which may be achieved over the character(s) or symbol(s) in the video game is determined both by the sophistication of the joystick used in the game and by the game program. Virtually all joysticks are capable of providing some directional control, for example, but the degree or precision of such directional control can vary greatly depending on the mechanical and/or electrical characteristics of the joystick. For example, a "4-way" joystick is movable between only four angular positions, 90.degree. apart and an "8-way" joystick is movable between 8 angular positions, 45.degree. apart. Other more sophisticated types of joysticks provide velocity, as well as directional control, by providing electrical output signals to the controller corresponding to the degree of deflection of the joystick from its initial parked or "detent" position. As with directional controls, the degree or precision of velocity controls can also vary greatly depending on the mechanical and/or electrical characteristics of the joystick.
It is known that high precision directional or velocity control may be achieved by using potentiometers in joystick controllers. One form of potentiometer which may be used for this purpose is an analog rotary potentiometer, which includes a shaft mounted for rotation about an axis such that rotation of the shaft communicates analog electrical signals to the controller. Where two such potentiometers are employed, they are normally coupled to the joystick structure along two orthogonal axes (e.g., an "x" and "y" axis) such that each individual potentiometer shaft rotates to a position corresponding to the displacement component of the joystick along one of the two axes. The combination of the two potentiometers can thereby communicate electrical signals to the controller corresponding to virtually any position of the joystick in a two-dimensional plane (e.g., the "x-y" plane). The electrical output signals, in turn, may be processed by the game controller to provide several hundreds of discrete variables for directional, velocity or other manner of control. Of course, the degree of control depends on the number and configuration of potentiometers employed in the joystick and the characteristics of the game program responsive to the potentiometer signals.
While analog joysticks generally offer tremendous advantages in control relative to other types of joysticks, both the degree of control which may be achieved by the joysticks and their failure rate can be compromised by the manner in which the potentiometers are mounted to the joystick structure. In particular, a common problem heretofore encountered in analog joysticks is side-loading of the potentiometer shafts. Side-loading may occur as a result of aggressive handling of the joystick controller during use and/or from "pre-loading" or fixedly mounting the potentiometer shaft in misalignment with the desired axis of rotation. In either case, the side-loading forces can result in eccentric rotation of the potentiometer shaft which can cause premature failure of the joystick and decrease its accuracy. This problem is generally exacerbated where the potentiometers are fixedly secured to the joystick structure as presently known (e.g., with a mounting nut) in a manner which does not permit the potentiometer some freedom of motion or "play" to dissipate the side-loading forces.
Moreover, with the present method of securing potentiometers to the joystick structure with a mounting nut, there is generally only a small, cramped space in the structure wherein the mounting nut is to be secured about the shaft of the potentiometer and, accordingly, the process of manipulating the mounting nut within such small space is generally a cumbersome, rather time consuming process.
Accordingly, there is a need for a method and apparatus for mounting potentiometers in a joystick controller in a manner that overcomes or at least reduces the effects of the side-loading problems and/or mounting difficulties discussed above. The present invention is directed to addressing this need.